In an earlier contribution to this discussion,
Peter Purr wrote:

I need to hang something from a single point on a ceiling. The load
will be about 300Kg max, after allowing a suitable safety factor
(actual load closer to 100Kg).

Any ideas or caveats?

I meant to look for a joist tonight in an out of the way location
(probably a cupboard), make a hole in the ceiling there & have a prod
about, as I'm not sure how much variation there is in possible
structure, but the battery's flat in my stud detector, so that'll have
to wait until tomorrow.

FWIW This concerns a flat in the middle storey of a small three storey
block, which was built in the 1970s. I won't have access to the floor
above, as that's obviously someone else's flat.


All but one of the replies so far have assumed that you have a wooden
structure - but it's worth checking whether this is *actually* the case. If
the building was purpose built as flats - as opposed to built as a house and
subsequently converted into flats - there's at least a chance that there's
concrete between the floors. Does your flat have a wooden floor, or is it
solid? If solid, then the one above will also be solid - in which case you
should be able - with suitable fixings - to screw an eye bolt into it from
which to hang your chair.

If the structure is wooden, you'll need to spread the load over several
joists. A large steel plate, attached to several joists with 100mm long 10mm
diameter carriage screws would probably do the job. Or if you don't mind
taking the ceiling down, you could bolt some hangers through the centreline
of several joists, and then bolt your plate to the hangers.
--
Cheers,
Roger
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